Designing topological edge states in bacterial active matter

Fuente: arXiv
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Hauptverfasser: Uchida, Yoshihito, Nishiguchi, Daiki, Takeuchi, Kazumasa A.
Format: Preprint
Veröffentlicht: 2026
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author Uchida, Yoshihito
Nishiguchi, Daiki
Takeuchi, Kazumasa A.
author_facet Uchida, Yoshihito
Nishiguchi, Daiki
Takeuchi, Kazumasa A.
contents Topology provides a unifying framework for understanding robust transport through protected edge states arising from nontrivial wavenumber topology. Extending these concepts to active matter, however, remains largely unexplored experimentally, with realizations limited to systems composed of chiral active particles. Here, we realize topological edge states in dense bacterial suspension, which represents a prototypical active matter system, using microfabricated geometrical structures with nontrivial wavenumber topology. Inspired by previous theoretical studies, we constructed a directional kagome network composed of ratchet-shaped channels that induce unidirectional bacterial flow. In this network, we found clear edge localization of bacterial density. A steady-state analysis based on the bacterial transport model and experimentally measured velocity field reveals how the characteristic collective flow generates edge localization. The model also uncovers the topological origin of the observed edge states. By tuning the geometry of the microfabricated networks, we identified directional channel design and network chirality as the key design features essential for the emergence of the edge state. Our results pave the way for establishing a control and design principle of topological transport in such active matter systems.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08243
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Designing topological edge states in bacterial active matter
Uchida, Yoshihito
Nishiguchi, Daiki
Takeuchi, Kazumasa A.
Soft Condensed Matter
Mesoscale and Nanoscale Physics
Statistical Mechanics
Biological Physics
Topology provides a unifying framework for understanding robust transport through protected edge states arising from nontrivial wavenumber topology. Extending these concepts to active matter, however, remains largely unexplored experimentally, with realizations limited to systems composed of chiral active particles. Here, we realize topological edge states in dense bacterial suspension, which represents a prototypical active matter system, using microfabricated geometrical structures with nontrivial wavenumber topology. Inspired by previous theoretical studies, we constructed a directional kagome network composed of ratchet-shaped channels that induce unidirectional bacterial flow. In this network, we found clear edge localization of bacterial density. A steady-state analysis based on the bacterial transport model and experimentally measured velocity field reveals how the characteristic collective flow generates edge localization. The model also uncovers the topological origin of the observed edge states. By tuning the geometry of the microfabricated networks, we identified directional channel design and network chirality as the key design features essential for the emergence of the edge state. Our results pave the way for establishing a control and design principle of topological transport in such active matter systems.
title Designing topological edge states in bacterial active matter
topic Soft Condensed Matter
Mesoscale and Nanoscale Physics
Statistical Mechanics
Biological Physics
url https://arxiv.org/abs/2601.08243